In the last years the topic administration of drugs by nasal inhalant has been more and more spreading, above all for the treatment of acute and chronic inflammatory processes and for pharmaceutical substances which otherwise have to be administered by parental (invasive) route. The nasal inhalant has the following advantages with respect to the oral or parental route:                the drug avoids the first passage effect and the gastro-intestinal metabolism,        the drug is quickly absorbed thanks to the high permeability and vascularisation of the nasal mucosa,        the administration route is not invasive and then minimizes the risk of infections,        a specific training is not requested for the administration,        trauma to the patient are not created.        
The topic treatments for both acute and chronic rhynosinusal pathologies have become of common use by otorhinolaryngolists and primary care physicians, in particular for the treatment of sinusitis and specifically of rhynosinusitis.
The sinusitis treatment has the following main objectives:                to re-establish the right drainages of the rhynosinual secretions,        to check or remove the inflammation source,        to ease the symptoms, above all pain and the sensation of nasal congestion.        
In order to reach such objectives actually different therapeutic options are applied, in particular:                cortico-steroidal anti-inflammatory drugs to reduce the inflammation and the mucosal edema,        mucolytic agents to fluidify the secretions,        antihistaminics to reduce secretions and the mucosal reactivity, especially in the allergic subject,        nasal decongestants to reduce the nasal obstruction,        anticholinergics to reduce secretions,        antibiotics to fight the infections.        
The intranasal administration of the above-mentioned drugs, with respect to the administration by oral route, can have the advantage of being a more rapid and not invasive route and of allowing to administer smaller doses with respect to the oral route, reaching directly the “target” site, with consequent smaller side effects.
The main targets of the nasal topic therapy are represented by:                the osteo-meatal complex, the structure near the ostium of the maxillary sinus, the most important site for draining the maxillary, etmoid and front sinus; an obstruction at such level on anatomical or inflammatory basis often represents the “primum movens” of a sinusal inflammation,        the (upper medium and above all the lower) nasal concha which, if inflamed, cause the drainage block of the sinuses and a reduction in the respiratory nasal space,        the rear portion of the nasal fossa and the sphenoethmoidal recess, drainage site of the sphenoidal sinus,        the paranasal sinuses themselves, by considering that in most cases the most involved sinuses in both acute and chronical inflammatory processes are represented by the maxillary sinus and by the etmoidal sinus.        
Such nasal topical treatments provide the nebulization of the substance to be administered in the rhynosinusal cavities. The nebulization, according to the sizes of the nebulized particles, can be performed in the form of spray or aerosol. The sizes of the nebulized particles influence the administration time and above all the penetration depth and the distribution of the nebulized substance in the rhynosinusal cavities.
In particular, the spray allows nebulizing the particles with larger diameter, it inserts a small quantity of product in the nasal cavities and it reaches easily the most anterior portion of the same cavities, in particular the head of the inferior nasal concha, by distributing in the most rear portions of the nasal fossae in small quantity by means of the mucociliary clearance.
The aerosol nebulization allows obtaining smaller particles, it allows administering a greater quantity of substance in the nasal fossae and obtaining, indeed thanks to the more limited diameter of the particles, the medium meatus and the deeper portions of the nasal fossae, by allowing a better distribution of the drug.
The drawbacks of the current systems of spray nebulization are mainly represented by:                reduced quantity of drug inserted in the nasal fossae,        distribution of the drug mainly at the level of the head of the inferior nasal concha and in the third inferior one of the nasal fossa and only in small quantity in the remaining portion of the nasal fossa,        rather high production and sale costs.        
In principle, the nebulization by means of aerosol is preferable from a therapeutic point of view in the treatment of the rhynosinusal cavities, by virtue of the better penetration and distribution of the drug. However, even the current systems of aerosol nebulization have some important drawbacks, and in particular:                long administration time,        the difficulty/impossibility of nebulizing viscous substances,        the need for often bulky devices, with need for outer energy source, typically an electric socket,        the engagement of keeping high hygiene standards downstream of each administration,        however rather high production and sale costs.        
It is also to be noted that several of the devices for nebulizing drugs in the rhynosinusal cavities in fact are conceived for inflammatory pathologies of the lower respiratory tracts and “adapted” for the rhynosinusal cavities themselves.